Infrared Wireless Microphone Systems
May 6, 2010 12:00 PM, By Bennett Liles
Not so long ago, the idea of sending wireless microphone signals on light rather than RF seemed fairly exotic, but with the new RF spectrum constraints, corporate training facilities and large K-12 and university campus environments are appearing as more fertile ground for infrared wireless microphone systems. In response, the number of IR wireless systems has expanded, bringing in a wider range of options and features. Infrared wireless systems have their limitations, but in the right applicationsuch as voice enhancement for multiclassroom instructionthey offer specific advantages that are unique to line-of-sight transmission, the top two of which are economical signal security and freedom from RF coordination issues. Instructors can roam freely from room to room without changing microphones or transmitters. In this survey, we have a look at what options are available in IR microphone systems for classroom instruction but exclude IR conferencing systems.
Designed for K-12 and higher-education classrooms, the Atlas Learn AL2430-2PH classroom security and sound-reinforcement system from Atlas Sound uses the AL-PH pendant/handheld microphone transmitter. This device provides local mobile control of mic volume, system volume, and mute settings through side-mounted soft-touch controls. Two AL-PH mic/transmitter units are included in the system. The receiver/amplifier has five sound source inputs for computer, TV/VCR, CD/DVD, aux, and paging, and 30W output power available on 8Ω, 25V, and 70.7V terminals. The page priority override mutes all other sound sources when a signal is present on the paging input channel. The AL-Dock unit is a wall- or table-mounted charging station that can accommodate two AL-PH microphones and four AA rechargeable batteries. Included with each system are two AL-IRDS dome sensors, each with a 10-meter-long RG-6 coax terminated in F connectors.
For applications requiring two IR wireless handheld microphones, the AWM6152 system from Audio 2000s offers two AWX6150 mics operating on 2.079MHz and 2.539MHz. The AWX6150 microphone uses two AA rechargeable NiMH batteries that can be charged by inserting either the base of the microphone or the batteries themselves into the ACC6152-01 charger. An LED indicator turns off when the batteries are fully charged. The AWR6152 receiver has two 1/4in. audio output jacks. If either is the only one connected, the output signal is a mono mix of both channels, but when both are connected, separate channels are output from each connector. There are four RCA infrared sensor connection ports and one IR sensor is included with the system. On the bottom of the receiver, there is a mic/line switch for setting the signal levels on the output jacks.
The IR-CS system from Azden combines the chest-worn IRN-10 mic/transmitter, the handheld IRH-15c mic/transmitter, the IRR-30P 2-channel receiver with power amplifier, and the IRD-60 dome sensor. Both mic units are 2-channel operating on 2.06MHz and 2.56MHz so they can be used simultaneously with the 2-channel receiver. CD/DVD players and other sources can be connected to the two stereo line-level inputs and played through the system along with the mics, and the receiver’s preamp level output can be used to feed videocameras. The main output can run four included ACS-6.5 in-ceiling loudspeakers or AWS-4.5 wall loudspeakers, delivering 5W to each at 4Ω. The dome sensor is powered from the receiver through the connecting RG-59 coax, and it includes a mounting bracket. The microphone/transmitter units each use two AA alkaline or rechargeable batteries to operate from 6 hours to 8 hours.
The Bogen Enhancer is an IR wireless system that includes the BCWBT body-pack transmitter, the BCHM headset mic, the BCLM lavalier mic, the BCBM body-pack mic, and the BCWHT handheld mic/transmitter. These all work with the BCWR 2-channel receiver, which has dual IR signal indicators, a mixed-channel output, separate channel volume controls, and two IR sensor coax inputs. The signal presence indicators light either red or green depending on whether the corresponding transmitter is turned on or off. The BCWBT body-pack transmitter has a channel-selector switch and a large IR emitter, and it runs on two AA alkaline or NiMH rechargeable batteries. The BCWHT handheld mic has a local on/off switch and an LED power indicator. Two BCIRS sensors are included, and each has a 35ft. cable.
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